Expansion cutter for sewer pipe cleaning



March 2, 1965 P. L. CIACCIO 3,171,149

EXPANSION CUTTER FOR SEWER PIPE CLEANING Filed May l0, 1963 34 WWW gps re@ L. anca/Q,

IN VEN TOR.

3,171,149 f nxransrors Curran non SEWER rmt CLEAMNG Peter L. Ciaccio, Culver City, Cal., assigner to Flexible ,f'ewertool Corporation, Lima, Sirio, a corporation of hio Filed May 10, 1963, Ser. No. 279,560 f 15 Claims. (Cl. 15-104.09)

This invention relates to sewer pipe cleaning tool of the rotary cutter type, driven by flexible cable, the cutter having a plurality of knives projecting in llaring formation from a hub which is secured to the forward end of a rotary drive cabie. The invention embraces the following objects:

(1) To provide a rotary cutter embodying a demountable assembly of hub parts and knives, readily convertible so as to vary the number of knives (e.g., from three-blade to two-blade or to six-blade assembly).

(2) To provide such a cutter embodying knives and hub parts which can readily be disassembled to change knives, to sharpen knives, or to vary the number of knives in an equaily spaced circumferential array, whileV providing a dependable high-torque transmitting coupling connections between the hub and the knives.

(3) To provide for radially contracting and expanding movements, such that the knives can contract to a smaller diameter when digging into an obstructing body of debris in a sewer pipe and can gradually expand to the full diameter of the pipe as they cut-away the debris.

(4) To provide a rotary cutter with an improved expandible array of cutter knives adapted to to be inserted into a sewer pipe of smaller diameter than the normal expanded diameter of the cutter.

(5) To provide such a cutter having an improved resilient mounting means in its hub', for resiliently urging the knives to expanded positions while yieldingly allowing contraction of the knives to reduced diameter.

(6) To provide such a cutter having improved means for transmitting high-torque rotary movement to the knives while allowing ythem freely to shift radially.

Other objects and advantages will become apparent in the ensuing specication and appended drawing in which:

FG. l is a perspective view of an expandible cutter embodying my invention;

FIG. 2 is a fragmentary side view of the same, partially in elevation and partially in axial section;

FIG. 3 is a transverse sectional View taken on the line 3 3 of FG. 2;

FIG. 4 is a plan view of the retainer washer for a 3- knife array;

FIG. 5 is a plan view of a retainer washer for a 2- knife array;

FIG. 6 is a side view of a cutter embodying a modified form of the invention shown partially in axial section and partially in elevation and illustrating knife positions of varying radii;

FIG. 7 is a fragmentary view partially in elevation and partially in axial section, of a cutter embodying another modified form of the invention; and

FIG. 8 is a perspective view of the segmental core of FIG. 7.

Referring now to the drawing in detail, and in particular to FIGS. 1-4 inclusive, I have shown therein, as an example of one form in which the invention may be embodied, a rotary sewer pipe cleaning cutter comprising, in general, an array of three knives indicated generally at A, a hub assembly B mounting the knife array A, and a drive element C on the forward end of which the hub assembly B is secured. The drive element C may be flexible cable, as shown, or may be solid drive rod, either continuous or sectional, all such drive elements being Well known in the art.

Each of the knives A is fabricated of a hard, tough` strap metal of moderate resiliency and a high degree of resistance to permanent deformation under bending stress. Each knife has a shank portion 15 for mounting it in the hub assembly B, a blade 16 projecting forwardly in aring relation to the other knives, and an inwardly curved tip 17 which has a skewed cutting edge 18 on its forward end. A beveled lateral cutting edge 1g ex tends along the leading margin of each blade 16 and around the curved tip portion 17 thereof.

The knife shank 15 is formed as a narrow segment of a hollow cone frustum to lit between the frusto-conical parts of the hub assembly B in which it is mounted. At its rear end it has a radially inwardly extending terminal abutment finger 21 which has a squared end 22 disposed chordally With reference to an intersecting concentric circle of the major axis of hub assembly B (FlG. 3).

Hub assembly B (FIG. 2) comprises a coupling sleeve 25 having a cylindrical bore Z6 in its rear end and an internally threaded bore 27 in its forward end. Drive element C is adapted to be socketed in the bore 26 and secured thereto by a set screw 28. A drive stem 31 having a cross section in the form of a regular polyhedron, has at its rear end a threaded shank 32 adapted to be threaded into the bore 27 and locked therein by a set screw 33. For most purposes, it is preferable to utilize a hexagonal form in the stem 31 as shown in FIG. 3, alternate flat sides of the stem being abutted by the terminal fingers 21 of the knives A with a ilat mating engagement as shown in FIG. 3. At its forward end, stem 31 has a threaded tip 34 on which is threaded a retainer nut 35.

Hub assembly B further includes a frusto-conical coupling collar 40 having at its small end an integral annular tip 41 provided with a centered polyhedral socket aperture 42 through which the stem 31 projects with a mating t so as to provide a rotary coupling connection between the stem and the collar 40. Re conic-segment Shanks 15 are adapted to mate against the internal wall of collar 40 and are coupled between the collar and the frusto-conical outer wall of a core 45 having an axial bore 46 through which the stem 31 extends. A drive and retainer washer 47 engages the base (forward end) of core i5 and is held by the abutting engagement of re tainer nut 35. In the periphery of washer 47 are a plurality of equally circumferentially spaced shallow chordal notches 48 the side extremities of which are defined by drive shoulders 49 constituting the lateral extremities of peripheral drive lugs 59. In its center, washer 47 has a polyhedral aperture 51 adapted to: receive the stem 31 with a close-coupled mating tit, thus providing a drive-coupling connection between the stem 5i and the washer 47. The washer 47 in turn provides a drive-coupling connection to the Shanks 15 of the knives A- oy the engagement of the Shanks 15 between shoulders 49 of notches 4S.

In FIG. 2, the core 45 is a rigid, non-compressible ring having a peripheral taper corresponding to that of the inner wall of collar 40, whereby the shanks 15 are snugly nested in a frusto-conical space S2 deiined between the core 45 and collar 4t?. The rearward pressure generated by nut 35 when tightened on stem tip 34, transmitted to the rear ends of knife Shanks 15 through the rear end of core 45, will tend to slide the Shanks rearwardly and inwardly in the collar 4t), thus tightly Wedging the squared ends 22 of terminal fingers 21 against the dat sides of stem 31. This wedging engagement positions the inner ends of Shanks 15 in equal eircumferentially spaced relation and in alignment with the notches 48, so that the biades will be tightly held in the positions in which they are designed to operate, resisting any tendency to be cocked circumferentially in response to the resistance of the debris against which they are being driven. By substituting the washer 47 of FIG. 5 for the washer 7, it is possible to assemble a cutter with two knives diametrically opposed, the terminal lingers 21 of their shanks engaging diametrically opposite faces of stem 31.

It would be possible 4to similarly convert to a six-knife cutter, by using a retainer washer with six notches, somewhat narrower, and with correspondingly narrowed knives, although the occasions for using such a cutter would be fewer than with the three and two-bladed cutters.

It will now be apparent that the invention provides an improved rotary cutter with demountable knives, readily convertible to selective knife arrays of differing numbers of knives, by the simple expedient of exchanging one drive washer for another and rearranging the positioning of the knives and their rear end abutting engagement with the faces of stem 31.

FIG. 6 illustrates a modified form of the invention wherein the core d5 is of rubber of moderate compressibility (eg, comparable to tire tread rubber) and has a periphery' of the same taper as the inner wall of collar 4t?. The core 45 is retained between the washer 47 and a smaller washer 55 engaging the apex end of the core, between that end and the terminal ngers 21 of the shanks i5. Radial yielding movement of the knives A is provided for by the compressibility of the core 45, the shanks t5 sinking into the segmental peripheral areas of he core engaged by them. The limited radial movements of the blades are accommodated by radial shifting of the Shanks 1S against the shoulders 49 in notches 48, while the blades continue to be tightly held against circumferentially yielding movements.

The FIG. 6 arrangement has the advantage of providing a yielding, resilient loading of the knives A to normally assume their positions of maximum expansion (e.g., as determined by engagement with the inner wall of collar 40). From these positions, the knives can yield inwardly, the compressible core 45 yielding in compression as the side margins of Shanks l5 slide in the notches 48 of the washer 47. The notches 4S are deep enough to accommodate the inward yielding of the knives (e.g., to the extent indicated by the broken line position shown in FIG. 6).

FIGS. 7 and 8 illustrate a yfurther modified form of the invention, wherein a core 45" of rubber having a compressibility equivalent to that of the core 45 of FIG. 6, is provided with segmental lateral grooves 56 in which the knife shanks are snugly fitted. The segmental conical periphery of the core 45 is fitted snugly to the inner wall of collar 40, the peripheral segments 57 of the core completely filling the spaces between the knife Shanks for the axial length of the core. As in the FIG. 6 form, the core 45 yields in compression to allow the knives to contract, and provides a resilient force which moves the knives to their positions of maximum expansion when no contracting force is applied to the knives. In each form of the invention, the washer 47 is coupled to the polyhedral periphery of stem 31 to transmit drive from the stem to the knives. Core 45" is retained between washers 47 and 55 the same as in FlG. 6.

In operation the skewed cutting edges i8 on the ends of the knives will operate with a slicing action against debris in a sewer pipe, and the lateral cutting edges 19 will operate with a scraping type of cutting action. Forward pressure against the cutter as it is being rotated will tend to cause the knives to contract toward lthe center of any obstructing mass of debris encountered by the cutter, with a wedging type of roaming action. As the debris is cleared away in any one spot, the knives will tend to spread until they establish contacti with the inner Wall of the sewer pipe. Thus the yielding'action permits the knives to assume various positions of contraction and expansion depending upon the conditions encountered in the sewer pipe, and a much more efficient cleaning action is thereby provided. In FIG. 6, the single knife A shown therein is illustrated in its expanded position in full lines and in a contracted position in broken lines. A section of the wall of a sewer pipe is indicated in phantom 'at 64?. A section of a pipe of smaller diameter into which the cutter can be inserted by contracting the blades, isi

illustrated in phantom at 60.

I claim:

l. In a rotary expansion cutter for sewer cleaning, in l combination: a plurality of cutter knives having respective mounting Shanks; and a hub assembly in which said Shanks are demountably secured in an annular array, comprising a driving stern adapted to receive rotary drive at its rear end, a frusto-conical collar and a core within said collar, said collar and core being mounted in coaxial assembly on said stern, with their larger ends facing forwardly and with said mounting shanks interposed radially between said collar and core; a drive and retainer washer mounted on said stem in opposed relation to the forward end of said core and coupled to said stem to receive drive therefrom, and securing means coupled to the forward end of said stem and arranged to apply axial retaining force to said washer which in turn is arranged to apply said retaining force to the forward end of said core to secure said knife shanks between said collar and core, said washer having a plurality of circumferentially-spaced peripheral drive lugs having respective radial shoulders as their circumferential extremities and defining between themselves respective peripheral notches through which said Shanks extend, said Shanks abutting said shoulders so as to receive drive therefrom.

2. A rotary expansion cutter as defined in claim l, wherein said core is of rigid material and has a frustoconical periphery spaced from the inner wall of said collar to provide an annular frusto-conical space in which said mounting Shanks are socketed so as to secure said knives in said annular array.

3. A rotary expansion cutter as defined in claim 1, wherein said core is of resilient compressible material, adapted to yield to radially inward tilting movements of said knives and to resiliently urge said array of knives toward an expanded condition, and wherein said Shanks are radially shiftable in said notches.

4. A rotary expansion cutter as defined in claim l, wherein said core is of compressible resilient material and includes a plurality of peripheral segments that are circumferentially spaced to define axially extending grooves receiving said knife Shanks.

5. A rotary expansionfcutter as defined in claim l, wherein said core is of resilient compressible material, adapted to yield to radially inward tilting movements of said knives and to resiliently urge said array of knives toward an expanded condition, and wherein said core has a plurality of axially extending grooves receiving the respective blade Shanks.

6. A rotary cutter as defined in claim l, wherein said core is of resilient compressible material, adapted to yield to radially inward tilting movements of said knives and to resiliently urge said array of knives toward an expanded condition, and wherein said core has a plurality of axially extending grooves receiving the respective blade Shanks and has, between said grooves, a plurality of peripheral surfaces of segmental-conical contour mating with the inner wall of said collar.

7. A rotary cutter as defined in claim l, wherein said core is of resilient compressible material, adapted to yield to radially inward tilting movements of said knives and to resiliently urge said array of knives toward an expanded condition, and wherein said core has a plurality of axially extending grooves receiving` the respective blade Shanks;

said hub further including a retainer washer engaging the apex end of said collar and containing it against rearward extrusion;

8. lr; a rotary expansion cutter for sewer cleaning, in combination: a plurality of cutter knives having respectivey mounting shanks; and a hub assembly in which said shanks are demountably secured, comprising a driving stem adapted to receive rotary drive at its rear end, a frusto-conical collar and a core within said collar, said collar and core being mounted in coaxial assembly on said stem, with their larger ends facing forwardly and with said mounting shanks interposed radially between said collar and core; a drive and retainer washer mounted on said stem in opposed relation to lthe forward end of said core and coupled to said stem to receive drive therefrom, and securing means coupled to the forward end of said stem and arranged to apply axial retaining force to said washer which in turn is arranged to apply said retaining force to the forward end of said core to secure said knife shanks between said collar and core, said washer having a plurality of circumferentially-spaced peripheral drive lugs having respective radial shoulders as their circumferential extremities and defining between them respective peripheral notches through which said shanks extend, said shanks abutting said shoulders so as to receive drive therefrom; said stem being of regular polyhedral prismatic form, and said drive Washer having a correspondingly polyhedral socket aperture receiving said stem and closely coupled thereto to receive drive therefrom.

9. A rotary cutter as defined in claim 8, wherein said collar has at its apex a lip defining a polyhedral socket aperture receiving said stern and closely coupled thereto to receive drive therefrom.

10. A rotary cutter as defined in claim 8, wherein said shanks have, at their rear ends, radially inwardly projecting terminal fingers with squared ends abutted against respective polyhedral faces of said stem, for aligning the rear ends of the knives.

11. A rotary cutter as defined in claim 8, wherein said shanks have at their rear ends, radially inwardly projecting terminal fingers with squared ends abutted against respective polyhedral faces of said stem, for aligning the rear ends of the knives; said securing means comprising a nut threaded onto said forward end of the stem and operable to apply axial pressure against said drive washer and core so as to wedge said shanks rearwardly into said collar, thereby causing said terminal fingers to be tightly wedged against their respective stem faces.

12. A rotary cutter as defined in claim 8, wherein said shanks have, at their rear ends, radially inwardly projecting terminal fingers with squared ends abutted against respective polyhedral faces of said stem, for aligning the rear ends of the knives; said core being of compressible material so as to yield to contracting movements of said array of knives, and said hub further including a retainer washer on said stem between said fingers and the apex end of said core and containing said apex end against rearward extrusion.

13. A rotary expansion cutter for sewer cleaning, comprising: a hub adapted to receive rotary drive; and a plurality of cutter knives having respective shanks-received in said hub and blade portions projecting forwardly therefrom in circumferentially spaced array; said hub including means for transmitting rotary drive to said knives and for securing said knives to resist circumferential displacement relative to said hub in response to torque'loads imposed on the cutter by the resistance of a mass of accumulated debris being reamed out by said cutter, while providing for limited radial expansion and contraction of said array of knives, said drive-transmitting means comprising a stem and a drive washer coupled to said stern to receive drive therefrom, said drive washer having a plurality of circumferentially-spaced peripheral drive lugs having respective radial shoulders as their circumferential extremities and defining between them respective peripheral notches through which said shanks extend, said shanks being shiftable radially in said notches while maintaining abutting drive-receiving engagement with said shoulders.

14. A rotary cutter as defined in claim 13, wherein said hub further includes a collar and a core mounted coaxially on said stem, with said core disposed within said collar and said shanks secured between the periphery of said core and the inner wall of said collar.

15. A rotary cutter as defined in claim 14, wherein said collar and core have frusto-conical inner and peripheral walls respectively, and wherein said knives project from said hub in correspondingly diverging array.

References Cited in the file of this patent UNITED STATES PATENTS 543,791 Wood July 30, 1895 2,069,871 Blanc Feb. 9, 1937 2,275,850 Gardner Mar. 10, 1942 2,288,771 Babcock July 7, 1942 2,517,227 OLeary Aug. 1, 1950 FOREIGN PATENTS 13,067 Great Britain July 7, 1900 

1. IN A ROTARY EXPANSION CUTTING FOR SEWER CLEANING, IN COMBINATION: A PLURALITY OF CUTTER KNIVES HAVING RESPECTIVE MOUNTING SHANKS; AND A HUB ASSEMBLY IN WHICH SAID SHANKS ARE DEMOUNTABLY SECURED IN AN ANNULAR ARRAY, COMPRISING A DRIVING STEM ADAPTED TO RECEIVE ROTARY DRIVE AT ITS REAR END, A FRUSTO-CONICAL COLLAR AND A CORE WITHIN SAID COLLAR, SAID COLLAR AND CORE BEING MOUNTED IN COAXIAL ASSEMBLY ON SAID STEM, WITH THEIR LARGER ENDS FACING FORWARDLY AND WITH SAID MOUNTING SHANKS INTERPOSED RADIALLY BETWEEN SAID COLLAR AND CORE; A DRIVE AND RETAINER WASHER MOUNTED ON SAID STEM IN OPPOSED RELATION TO THE FORWARD END OF SAID CORE AND COUPLED TO SAID STEM TO RECEIVE DRIVE THEREFROM, AND SECURING MEANS COUPLED TO THE FORWARD END OF SAID CORE AND COUPLED TO STEM TO RECEIVE DRIVE FORCE TO SAID WASHER WHICH IN TURN IS ARRANGED TO APPLY SAID RETAINING FORCE TO THE FORWARD END OF SAID CORE TO SECURE SAID KNIFE SHANKS BETWEEN SAID COLLAR AND CORE, SAID WASHER HAVING A PLURALITY OF CIRCUMFERENTIALLY-SPACED PERIPHERAL DRIVE LUGS HAVING RESPECTIVE RADIAL SHOULDERS AS THEIR CIRCUMFERENTIAL EXTREMITIES AND DEFINING BETWEEN THEMSELEVES RESPECTIVE PERIPHERAL NOTCHES THROUGH WHICH SAID SHANKS EXTEND, SAID SHANKS ABUTTING SAID SHOULDERS SO AS TO RECEIVE DRIVE THEREFROM. 